Then i can't help you, Use whatever works and it's trustworthy enough for you, just don't be surprised and come crying if Bitwarden SOMEHOW gets a security breach.
I don't even have a nextcloud, i just keep my database on a single folder sync across my tablet and phone, if you could set up the nextcloud to sync in rhat same folder you (theorically) would have no problems 🤔
I personally use Disroot along with Thunderbird 😁